Compaction machines are used for compacting soil substrates. More particularly, after application of an asphalt layer on a ground surface, a compaction machine is moved over the ground surface in order to achieve a planar ground surface. The compaction machine generally includes single or dual vibrating compactor drums. The compactor drums generally include a vibration system that transfers vibrations to the ground surface in order to impose compaction forces for leveling the ground surface.
The compactor drums may include a conventional dual amplitude vibratory system. Such dual amplitude vibratory systems may include a fixed weight that is a rotatable eccentric lobe and a non-fixed weight. The non-fixed weight shifts a center of gravity of the dual amplitude vibratory system in order to create two different vibration amplitudes depending upon a direction of rotation of the vibratory system.
U.S. Pat. No. 6,637,280 describes a vibratory mechanism provided with first and second motors connected to first and second eccentric weights. One of the first and second motors is operable to change a phase difference between the first and second eccentric weights to change a vibration amplitude.